Blockchain is a chained data structure that is connecting data blocks in chronological order, and it is a distributed ledger that is immutable and unforgeable guaranteed by cryptography, where the ledger records digital asset derived from cryptography. All in all, blockchain technology is a whole new distributed infrastructure and computed mode that utilizes chained-block data structure to authenticate and store data, that utilizes distributed nodes consensus algorithm to generate and update data, that utilizes cryptography to protect data transmission and access, that utilizes smart contracts which are formed by automated scripts to program and process data.
Centralized exchange is a centralized platform or application, which allows users to trade fiat currencies or one type of cryptocurrencies with other types of cryptocurrencies. Users directly deposit cryptocurrencies into exchange, which helps store capital as a wallet until orders are generated. Centralized exchanges have high trading efficiency and good user experience, but they suffer from crucial defects such as low security.
Decentralized exchange is differentiated from centralized exchange in that user assets in a decentralized exchange are not controlled by a single institution or platform. In the whole life cycle of a transaction, user assets are under the full control of the users themselves or decentralized communities or organizations. Decentralized exchanges are more robust to security attacks, but they suffer from low trading efficiency and bad user experience.